OBJECTIVETo provide an appropriate angle and depth of needle insertion in acupuncture at Zusanli (ST 36) and avoid injuring the nerve and blood vessel and exert the most effect.

METHODSEighty adult lower-limb samples were used to dissect and observe the relative layered structures and adjoining important nerves and blood vessels in needling Zusanli (ST 36) according to the national standard.

RESULTSThe needling depth from the skin to the interosseous membrane and from the skin to posterior border of tibialis posterior is (2.22 +/- 0.31) cm and (4.42 +/- 0.53) cm, respectively. There are flabellate branches of anterior tibial arteries and deep peroneal nerves around the needle in the superficial layer of interosseous membrane. The vessel and nerve bundles containing tibial nerve and posterior tibial vessels can be touched when the needle body past through tibialis posterior.

CONCLUSIONIt is recommended that ideal average depth of acupuncture is 2.22 cm and the maximum depth is 4.42 cm for oblique needling Zusanli (ST 36). When it is injected, the needle should be perpendicularly inserted or deviated slightly to the direction of tibia and paralleled to medial surface of tibia. And the safe needling depth is generally less than 5 cm. The point of the body surface between tibialis anterior and extensor digitorum longus at 3 cun below Dubi (ST 35) is also an effectively stimulating point.